In such rotary pumps, the design of the synchronous motor does not allow definition of an invariable starting direction for the rotor, and thus a specific direction for the rotation of the impeller connected to the rotor. Consequently, the shape in which the turbine is made must allow an identical output regardless of its rotating direction, which corresponds to the direction in which the rotor starts when the pump is activated. In practice, because of this constraint, turbines are made with radial blades whose configuration does not allow optimization of the output of the electrically-driven rotary pumps of the type considered herein.